tolong di bantu no 19.......

ABC
180 =40+7x
180-40 = 7x
140 = 7x
x = 20


ACB
180 =80+2y
180-80 = 2y
100 = 2y
y= 50

BAC
180 = 5z + 40 + (2×50)
180 = 5z + 40 + 100
180 = 5z + 140
180-140 = 5z
40 = 5z
z = 8

7x+40=180
7x=140
x=20

80+2y=7x ( dlm besebrangan)
80+2y=7.20
2y=140-80
2y=60
y=30

5z+40+2y=180
5z+40+2.30=180
5z=180-40-60
5z=80
z=16

x+y+z=20+30+16=66 (A)